Fix the board so that it doesn't move either with tape or something else.
Make sure all the pads are clean, if not then clean it with steel wool.
Put some flux on one pad and then put a dab of solder on the surface to evenly cover the surface of that pad.
Make sure the Surface mount component pin which should connect on that pad is clean.
Put some flux on the pin and place the component carefully so that pin is over the solder covered pad and then just touch the iron to attach the pin.
Check if all pins align. If not then reheat the pin and then adjust the component to align all pads. Don't keep the heat on the pin for more than 10 seconds.